trying to put a hole in a rigged character for animation
You can go into edit mode, select the vertices that should create the hole and press P to separate the selected elements. This creates a new object which retains all previous behaviours: parenting, armature, weights, modifiers, ecc ... You will have to add a bone for this new feature and do some manual weighting..

Another way is using shape keys: create 2 new shapekeys, then with the second selected go into edit mode and change the shape of the mesh until the hole looks the way you want, then in object mode you can animate the shape key value.

Using AninAll on vertices that have been animated by a rig can lead to unpredictable results.